Embolectomy catheters and methods for treating stroke and other small vessel thromboembolic disorders

ABSTRACT

Embolectomy catheters, rapid exchange microcatheters, systems and methods for removing clots or other obstructive matter (e.g., thrombus, thromboemboli, embolic fragments of atherosclerotic plaque, foreign objects, etc.) from blood vessels. This invention is particularly useable for percutaneous removal of thromboemboli or other obstructive matter from small blood vessels of the brain, during an evolving stroke or period of cerebral ischemia. In some embodiments, the embolectomy catheters of this invention are advanceable with or over a guidewire which has been pre-inserted through or around the clot. Also, in some embodiments, the embolectomy catheters include clot removal devices which are deployable from the catheter after the catheter has been advanced at least partially through the clot. The clot removal device may include a deployable wire nest that is designed to prevent a blood clot from passing therethrough. The delivery catheter may include telescoping inner and outer tubes, with the clot removal device being radially constrained by the outer tube. Retraction of the outer tube removes the constraint on the clot removal device and permits it to expand to its deployed configuration. An infusion guidewire is particularly useful in conjunction with the embolectomy catheter, and permits infusion of medicaments or visualization fluids distal to the clot.

The present invention is a continuation of U.S. patent application Ser.No. 10/730,860, now U.S. Pat. No. 7,691,121 filed Dec. 9, 2003, which isa continuation of U.S. patent application Ser. No. 09/437,530 filed Nov.10, 1999 (now U.S. Pat. No. 6,685,722 issued Feb. 3, 2004), which is acontinuation-in-part of U.S. patent application Ser. No. 09/071,561filed May 1, 1998 (now U.S. Pat. No. 6,511,492 issued Jan. 28, 2003),all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to medical methods and devices,and more particularly to thrombolectomy catheters, and methods for usingsuch catheters, for removing blood clots or other matter from the lumensof blood vessels or other anatomical conduits.

BACKGROUND OF THE INVENTION

Various types of thromboembolic disorders, such as stroke, pulmonaryembolism, peripheral thrombosis, atherosclerosis, and the like, areknown to occur in human beings and other mammals. Such thromboembolicdisorders are typically characterized by the presence of athromboembolus (i.e., a viscoelastic blood clot comprised of platelets,fibrinogen and other clotting proteins) which has become lodged at aspecific location in a blood vessel.

In cases where the thromboembolism is located in a vein, the obstructioncreated by the thromboembolus may give rise to a condition of bloodstasis, with the development of a condition known as thrombophlebitiswithin the vein. Moreover, peripheral venous embolisms may migrate toother areas of the body where even more serious untoward effects canresult. For example, the majority of pulmonary embolisms are caused byemboli that originate in the peripheral venous system, and whichsubsequently migrate through the venous vasculature and become lodgedwith the lung.

In cases where the thromboembolus is located within an artery, thenormal flow of arterial blood may be blocked or disrupted, and tissueischemia (lack of available oxygen and nutrients required by the tissue)may develop. In such cases, if the thromboembolism is not relieved, theischemic tissue may become infarcted (i.e., necrotic). Depending on thetype and location of the arterial thromboembolus, such tissue infarctioncan result in death and amputation of a limb, myocardial infarction, orstroke. Notably, strokes caused by thromboemboli which become lodged inthe small blood vessels of the brain continue to be a leading cause ofdeath and disability, throughout the world.

In modern medical practice, thromboembolic disorders are typicallytreated by one or more of the following treatment modalities:

-   -   a) pharmacologic treatment wherein thrombolytic agents (e.g.,        streptokinase, urokinase, tissue plasminogen activator (TPA))        and/or anticoagulant drugs (e.g., heparin, warfarin) are        administered in an effort to dissolve and prevent further growth        of the clot;    -   b) open surgical procedures (e.g., surgical embolectomy or clot        removal) wherein an incision is made in the blood vessel in        which the clot is lodged and the clot is removed through such        incision-sometimes with the aid of a balloon-tipped catheter        (e.g., a “Fogarty Catheter”) which is passed through the        incision and into the lumen of the blood vessel where its        balloon is inflated and used to extract the clot out of the        incision; and,    -   c) transluminal catheter-based interventional procedures wherein        a clot removing/disrupting catheter (e.g., a suction-type        catheter having a suction tip, clot-capturing type catheter        having a clot capturing receptacle (e.g., a basket, coil, hook,        etc.), or clot-disrupting catheter having a clot disrupting        apparatus (e.g., an ultrasound probe or laser)) is        percutaneously inserted and advanced through the        patient'vasculature to a location adjacent the clot. The suction        tip, clot capturing receptacle or clot disrupting apparatus is        used to aspirate, capture & remove, disrupt or ablate the        offending clot.

Each of the above-listed treatment modalities has its own set ofadvantages and disadvantages. For example, pharmacologic treatment hasthe advantage of being non-invasive and is often effective in lysing ordissolving the clot. However, the thrombolytic and/or anticoagulantdrugs used in these pharmacologic treatments can cause untoward sideeffects such as bleeding or hemorrhage. Also, in cases where time is ofthe essence, such as cases where an arterial thromboembolism is causingsevere tissue ischemia (e.g., an evolving stroke or an evolvingmyocardial infarction) the time which may be required for thethrombolytic drugs to fully lyse or dissolve the blood clot and restorearterial blood flow may be too long to avoid or minimize the impendinginfarction.

Open surgical thrombus-removing procedures can, in many cases, be usedto rapidly remove clots from the lumens of blood vessels, but such opensurgical procedures are notoriously invasive, often require generalanesthesia, and the use of such open surgical procedures is generallylimited to blood vessels which are located in surgically accessibleareas of the body. For example, many patients suffer strokes due to thelodging of blood clots in small arteries located in surgicallyinaccessible areas of their brains and, thus, are not candidates foropen surgical treatment.

Transluminal, catheter-based interventional procedures are minimallyinvasive, can often be performed without general anesthesia, and can insome cases be used to rapidly remove a clot from the lumen of a bloodvessel. However, such catheter-based interventional procedures arehighly operator-skill-dependent, and can be difficult or impossible toperform in small or tortuous blood vessels. Thus, patients who sufferstrokes due to the presence of clots in the small, tortuous arteries oftheir brains may not presently be candidates for catheter-based,transluminal removal of the clot, due to the small size and tortuosityof the arteries in which their clots are located.

In concept, the trasluminally deployable clot capturing type ofcatheters could be useable in ischemic strokes, because they aretypically capable of removing an offending blood clot without the needfor suction or application of energy (e.g., laser, ultrasound) whichcould be injurious to the delicate, small blood vessels of the brain.However, none of the prior art trasluminally deployable clot capturingtype of catheters are believed to be of optimal design for use in thesmall blood vessels of the brain because they are a) not equipped withappropriate guidewire passage lumens to allow them to be passed overpreviously inserted, small-diameter (e.g., 0.006-0.018 inch) guidewires,b) they are not adapted for rapid exchange over a guidewire of standardlength (e.g., a guidewire which is less than twice the length of thecatheter) and c) the clot capturing receptacles of these catheters arenot optimally constructed and configured for removal of clots from verysmall blood vessels as are typically found in the brain.

Examples of transluminally deployable clot-capturing type embolectomycatheters of the prior art include those described in U.S. Pat. No.4,706,671 (Weinrib), U.S. Pat. No. 4,873,978 (Ginsburg), U.S. Pat. No.5,011,488 (Ginsburg), and U.S. Pat. No. 5,895,398 (Wensel, et al.). The'390 patent to Wetzel, et al., discloses a clot capture device where asmall catheter is first passed in a distal direction through aviscoelastic clot. A clot capture coil mounted to a stiff insertionmandrel is then advanced through the catheter and deployed on the distalside of the clot. The clot capture coil may be a plurality of wireshaving shape memory which radially expand into a variety of shapes that,when the insertion mandrel is retracted, ensnare the clot for removal.Despite extensive development in this area, for the reasons stated aboveand/or other reasons, none of the prior art embolectomy catheters arebelieved to be optimally designed for treating ischemic stroke.

Thus, there exists a need for the development of a new transluminallyinsertable, clot-capturing type embolectomy catheters which areadvanceable and exchangeable over pre-inserted small diameterguidewires, and which are constructed to rapidly and selectively removeblood clots or other matter from small, delicate blood vessels of thebrain, so as to provide an effective treatment for evolving strokes andother thromboembolic disorders.

SUMMARY OF THE INVENTION

The present invention generally comprises an embolectomy catheter deviceand method for removing blood clots or other matter from the lumens ofblood vessels or other anatomical conduits of a mammalian body. Theembolectomy catheters and methods of the present invention areparticularly suitable for use in removing clots or thromboemboli fromsmall arteries of the mammalian brain to prevent or minimize theseverity of stroke.

A. Embolectomy Catheters of the Present Invention

In one aspect of the present invention, an embolectomy catheter forremoving a blood clot or other such obstructive matter from a bloodvessel is provided. The embolectomy catheter includes an elongateflexible catheter body having a proximal end, a distal end, an innertube, and a guidewire lumen a part of which extends longitudinallythrough the inner tube. A clot removal device on the inner tube isdeployable in a first state to a radially expanded configuration. Aguidewire is sized to passed through the inner tube and project distallyfrom the distal end of catheter body.

The catheter desirably includes an outer tube arranged to surround andconstrain the clot removal device about the inner tube in a second stateprior to its deployment to the first state. Both the catheter body andthe clot removal device are passable through the clot in the secondstate. The catheter also may include a handle whereby an insertionportion of the catheter body extends distally from handle. The insertionportion includes the inner tube and outer tube, both extendingsubstantially to the distal end of the catheter body. The inner andouter tubes are preferably relatively axially displaceable to cause theclot removal device to transition between the first and second state.

In a preferred embodiment, the clot removal device has a proximal endand a distal end, the distal end being attached to the inner tube andthe proximal end being free to slide axially over the inner tube. Theproximal end of the clot removal device is axially displaced away fromthe distal end within the outer tube so as to longitudinally stretch andradially constrain the device in the second state prior to itsdeployment to the first state. The clot removal device may take avariety of forms, but is preferably a plurality of separate wiresattached at their distal ends to the inner tube and helically wound orlooped about the inner tube at their proximal ends. In the first,deployed state, the plurality of helically wound wires radially expandsinto a tangled nest which is suitable for capturing the clot. Desirably,a marker band is arranged to slide longitudinally with the proximal endof clot removal device to indicate to operator the deployment state.Marker bands on both the inner and outer tubes provide further relativeposition indications.

In accordance with a further aspect of the invention, an embolectomycatheter for removing a blood clot or other such obstructive matter froma blood vessel comprises an elongate flexible catheter body having aproximal end, a distal end, an axis extending from a proximal end to thedistal end, an inner tube, and an outer tube terminating just short of adistal end of catheter body. The clot removal device on the inner tubeis initially collapsed and constrained in its collapse configuration bya portion of the outer tube. A distal tip of the catheter body locatedon the inner tube is adapted to pass through the blood clot to beremoved. The outer tube is axially retractable to remove the constrainton the clot removal device such that it may radially expand to adeployed configuration.

Preferably, the outer tube extends distally within a proximal mouth ofthe distal tip prior to being retracted. The inner tube may bereinforced along its entire length, and is preferably more flexible atits distal end than at its proximal end. In addition, both the inner andouter tubes may include discrete segments that become more flexible in adirection from the proximal end to the distal end. In one embodiment,the catheter body has a size of between approximately 1-5 French at itsdistal end, and is preferably about 3 French.

A further aspect of present invention includes a handle attached to aproximal end of an insertion portion of catheter body. An actuator isprovided on handle for proximally displacing the outer tube with respectto the inner tube in order to deploy the clot removal device. In oneembodiment, the actuator comprises a slide movable along the handle andattached to the outer tube, the slide including a through bore forreceiving an extension of the inner tube. An infusion port on the slideenables infusion of fluid in the annular space between the inner andouter tubes.

A further embolectomy catheter device of the present invention generallycomprises; a) an elongate, pliable clot penetrating catheter which isadvanceable, distal end first, through the clot or other obstructivematter (e.g., thrombus, thromboembolus, pieces of detachedatherosclerotic plaque, foreign matter, etc.) which is to be removed,and b) a matter capturing receptacle which is deployable from the distalend of the catheter after it has been advanced through the obstructivematter, to capture and facilitate removal of the obstructive matter. Thematter capturing receptacle is initially disposed in a first or stowedconfiguration wherein the receptacle is in a radially collapsedcondition and contained upon or within the catheter or otherwisesufficiently compact to pass through the clot or other obstructivematter. Thereafter, the matter capturing receptacle is deployable (e.g.,advanceable, projectable and/or expandable) from the catheter such thatit assumes a second or expanded configuration wherein the receptacle mayreceive and at least partially surround the distal aspect of the clot orother obstructive matter so as to facilitate extraction and removal ofthe blood clot or other obstructive matter along with the catheter.

A guidewire lumen may extend longitudinally through the entire length ofthe catheter (i.e., an “over-the-wire” embodiment) or through only adistal portion of the catheter (i.e., a “rapid exchange” embodiment). Ineither of these embodiments of the catheter, the guidewire lumen mayextend through the matter capturing receptacle such that the catheter(with its matter capturing receptacle in its collapsed or stowedconfiguration) may be advanced over a guidewire which has previouslybeen passed through the vessel-obstructing clot or other obstructivematter. Such arrangement of the guidewire lumen additionally allows theembolectomy catheter to be exchanged (e.g., removed and replaced withanother embolectomy catheter or another type of catheter) if suchexchange should become necessary or desirable. This ability to allow theguidewire to remain positioned through the offending clot or otherobstructive matter may serve to ensure that the catheter or itsreplacement can be re-advanced through the clot or other obstructivematter to its desired position.

The matter capturing receptacle of the catheter may comprise a distalobstructive matter-engaging portion (e.g., a coil, basket or concavemember) of porous construction (e.g., a woven, coiled or mesh structureformed of wire, fiber or fabric), which is attached to the catheter byway of one or more proximal struts (e.g. connector members (e.g., aplurality of thin wires or struts). Initially, with the matter capturingreceptacle disposed in its first (e.g., collapsed or stowed)configuration, the distal end of the catheter is advanced through theclot or other obstructive matter. After the catheter has been advancedthrough the clot or other obstructive matter, the matter capturingreceptacle is moved to its second (e.g., expanded or operative)configuration, such that the distal obstructive matter-engaging portionof the receptacle will contact and/or at least partially surround thedistal aspect of the clot or other obstructive matter. The distalobstructive matter-engaging portion of the receptacle is preferably ofpermeable construction to permit blood to flow therethrough, but issufficiently dense (i.e., sufficiently impermeable) to prevent the clotor other obstructive matter from passing therethrough. In this manner,the distal obstructive matter-engaging portion of the receptacle isuseable to retract or draw the clot or other obstructive matter, in theproximal direction, from its then-present location. The proximalstrut(s) which extend between the receptacle to the catheter aretypically of radially splayed or outwardly angled configuration andis/are preferably configured, oriented and positioned so as to slice,cut or otherwise pass through the matter of the clot or otherobstructive matter, when deployed at a site distal to the clot or otherobstructive matter and subsequently retracted in the proximal direction.To assist such proximal strut(s) in passing through the clot or otherobstructive matter, energy (e.g., radio-frequency energy, vibration,heat, etc) may be applied to the proximal strut(s) during their proximalretraction through the clot or other obstructive matter.

A contrast medium injection port may be formed on the proximal portionof the embolectomy catheter, to allow radiographic contrast medium(e.g., dye) to be injected through the catheter while a guidewireremains positioned within the guidewire lumen.

B. Rapid Exchange Microcatheter Useable in Conjunction with EmbolectomyCatheters of the Present Invention

Further in accordance with the present invention, there is provided arapid exchange microcatheter which comprises a small diameter flexiblemicrocatheter of a type commonly used in neuroradiology procedures(e.g., Prowler™ microcatheter, Cordis Endovascular Systems, Miami Lakes,Fla.), which has greater flexibility at or near its distal end than ator near its proximal end, and which includes in accordance with thisinvention, the addition of a guidewire passage port formed in thesidewall of the catheter, at a spaced distance (e.g., 0.5-35 cm) fromits distal tip. A guidewire deflector may be formed within the mainlumen of the catheter adjacent to the guidewire passage aperture, todeflect the proximal end of a guidewire out of the guidewire passageaperture as the catheter is advanced over the guidewire. The formationof such guidewire passage aperture and guidewire deflector allows aguidewire to be passed through only a distal portion of the catheterlumen. This lumen arrangement allows the microcatheter to be exchanged(i.e., removed and replaced by another microcatheter or an embolectomycatheter of the above-summarized design) while the operator holds theguidewire in place by grasping the exteriorized proximal end of theguidewire—even in instances where a standard length guidewire (i.e., notan “exchange-length” guidewire) is used.

C. Methods of the Present Invention for Removing Clots or Other Matterfrom Blood Vessels

The present invention also contemplates methods of removing clots orother obstructive matter from blood vessels. One method includes the useof a guidewire to first pierce and traverse at least portion of the clotto be removed. An embolectomy catheter of the present invention isadvanced either with or over the guidewire and through the clot. A clotremoval device provided on the catheter is then deployed radiallyoutwardly, and the catheter retracted to entangle the clot removaldevice with the clot. Further retraction of the catheter in combinationwith optional suction removes the clot.

In a further method of the present invention, the guidewire includes aninfusion lumen therein. After the guidewire is inserted through theclot, medication or clot dissolution fluid may be administered to thedistal side of the clot. Alternatively, visualization fluid may beinjected to obtain a better picture of the clot from the distal sidethereof.

Further in accordance with the present invention, there are provided amethod for treating ischemic stroke caused by a thromboembolism whichhas become lodged in a small blood vessel of the brain (i.e., bloodvessels located in, on or around the brain). The method of the presentinvention may be carried out using the rapid-exchange microcatheters andembolectomy catheters of the present invention. An exemplary methodgenerally comprises the steps of:

A. percutaneously inserting a guidewire (alone or in combination with aguide catheter) into an intracranial blood vessel, using the Seldingertechnique or other appropriate method of percutaneous guidewireplacement;

B. advancing a microcatheter over the guidewire, or separately from theguidewire, through the vasculature until the microcatheter is near thesite at which the blood clot or other obstructive matter is located;

C. passing radiographic contrast medium (e.g., dye) through themicrocatheter under radiographic visualization to verify the exactlocation of the obstructive matter and/or to map the vascular anatomy inthe area of the obstruction;

D. advancing the guidewire (or a separate small guidewire) through themicrocatheter until such guidewire becomes located in a desiredoperative position relative to the obstructive matter (e.g., such thatits distal end has fully or partially traversed or passed through thethromboembolism or other obstructive matter);

E. withdrawing and removing the microcatheter while substantiallymaintaining the small guidewire in its operative position (e.g.,preventing the guidewire from moving so far as to lose the access to theobstructive matter that the presence of the guidewire provides);

F. advancing a matter-capturing type embolectomy catheter (such as anembolectomy catheter of the present invention) which has an obstructivematter-capturing receptacle deployable therefrom, over the operativelypositioned guidewire until the distal end of the embolectomy catheterhas advanced fully or at least partially through the obstructive matter(e.g., has penetrated through an obstructive thromboembolism);

G. optionally injecting radiographic contrast medium through a lumen ofthe embolectomy catheter to guide or verify the positioning of theembolectomy catheter relative to the lodged blood clot or otherobstructive matter;

H. deploying the obstructive matter-capturing receptacle of theembolectomy catheter such that it assumes its second or expandedconfiguration at a site which is distal (i.e., downstream) of the lodgedblood clot or other obstructive matter;

I. retracting the obstructive matter-capturing receptacle such that aproximal portion of the receptacle (i.e., proximal struts) passesthrough the thromboembolism and at least a portion of the clot or otherobstructive matter becomes located within the obstructivematter-receiving portion of the obstructive matter-capturing receptacle;

J. optionally injecting radiographic contrast medium through a lumen ofthe embolectomy catheter to determine whether blood flow has beenrestored through the region of the blood vessel which had previouslybeen deprived of blood flow due to the presence of the clot or otherobstructive matter; and,

K. retracting the embolectomy catheter to remove the blood clot or otherobstructive matter from the body (e.g., withdrawing the embolectomycatheter and the extracted clot or other obstructive matter through thepercutaneous entry tract through which the catheter had previously beeninserted).

Thus, by the above-summarized method of the present invention, the bloodclot or other obstructive matter which is causing an ischemic (i.e.,thrombotic or embolic) stroke is removed and arterial blood flow isrestored to the region of the brain which had become ischemic due to thelodging on the offending blood clot or other obstructive matter withinthe blood vessel.

D. Infusion Guidewire

An infusion guidewire of the present invention preferably comprises aninnerwire and an outer sheath slideable thereover. The wire and sheathare first advanced together through the clot, and the innerwire is thenretracted to open a lumen within the outer sheath. Advantageously, theouter sheath, or sheath and inner wire combination, can remain in placethrough the clot while different catheters are exchanged thereover.

Further elements, objects and advantages of the present invention willbecome apparent to those of skill in the art upon reading andunderstanding of the following detailed description of preferredembodiments and consideration of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a human patient having a firstembodiment (an “over-the-wire” embodiment) of an embolectomy catheter ofthe present invention operatively inserted for the purpose of removing ablood clot or other obstructive matter from a small blood vessel of thebrain.

FIG. 1A is a perspective view of the embolectomy catheter device of FIG.1 operatively positioned upon a guidewire, and having its obstructivematter-capturing receptacle disposed in an expanded configuration.

FIG. 2A is an enlarged longitudinal sectional view of the distal end ofthe over-the-wire embolectomy catheter of FIG. 1 with its obstructivematter-capturing receptacle in a first or stowed position.

FIG. 2B is an enlarged, broken, longitudinal sectional view of thedistal end of the over-the-wire embolectomy catheter of FIG. 1 with itsobstructive matter-retrieving member in a distally advanced position andits obstructive matter-capturing receptacle disposed in a fully expandedconfiguration.

FIG. 2C is a cross-sectional view through line 2C-2C of FIG. 2A.

FIG. 2D is a cross-sectional view through line 2D-2D of FIG. 2A.

FIG. 2D′ is a cross-sectional view through line 2D-2D of FIG. 2A,modified to show an alternative mode of constructing the guide bores inthe distal tip member, through which the wires which form theobstructive matter-capturing receptacle extend.

FIG. 3A is an enlarged, broken, longitudinal sectional view of thedistal end of the over-the-wire microcatheter of the prior art.

FIG. 3B is an enlarged, broken, longitudinal sectional view of thedistal end of a second embodiment (i.e., another over-the-wireembodiment) of an embolectomy catheter of the present invention.

FIG. 3B′ is a cross-sectional view through line 3B′-3B′ of FIG. 3B.

FIG. 3C is an enlarged, broken, longitudinal sectional view of thedistal end of a rapid exchange microcatheter of the present invention.

FIG. 3C′ is a cross-sectional view through line 3C′-3C′ of FIG. 3C.

FIG. 3D is an enlarged, broken, longitudinal sectional view of thedistal end of a third embodiment (i.e., a rapid exchange embodiment) ofan embolectomy catheter of the present invention.

FIG. 3D′ is a cross-sectional view through line 3D′-3D′ of FIG. 3D.

FIG. 3E is an enlarged, longitudinal sectional view of the distal end ofa fourth embodiment (i.e., another rapid exchange embodiment) of anembolectomy catheter of the present invention.

FIG. 3E′ is a cross-sectional view through line 3E′-3E′ of FIG. 3E.

FIG. 3F is an enlarged, longitudinal sectional view of the distal end ofa fifth embodiment (i.e., another rapid exchange embodiment) of anembolectomy catheter of the present invention.

FIG. 3F′ is a cross-sectional view through line 3F′-3F′ of FIG. 3F.

FIG. 4 is a perspective view of the third embodiment (i.e., a rapidexchange embodiment) of an embolectomy catheter of FIG. 3D having aguidewire operatively inserted through its guidewire lumen and itsobstructive matter capturing receptacle in its deployed, radiallyexpanded position.

FIG. 5 is a perspective view of a first alternative obstructivematter-capturing receptacle which may be incorporated into any of theembolectomy catheters of the present invention.

FIG. 5′ is an enlarged view of portion 5′ of FIG. 5.

FIG. 5″ shows an alternative construction for portion 5′ of FIG. 5.

FIG. 5A is a distal end view of FIG. 5.

FIG. 5B is a perspective view of a second alternative obstructivematter-capturing receptacle which may be incorporated into any of theembolectomy catheters of the present invention.

FIG. 5B′ is a perspective view of the second alternative obstructivematter-capturing receptacle of FIG. 5B having a clot capturedtherewithin and with its support spines being partially retracted intothe catheter.

FIG. 5B″ is a perspective view of the second alternative obstructivematter-capturing receptacle of FIG. 5B having a clot capturedtherewithin and with its support spines being further retracted into thecatheter so that the obstructive matter capturing receptacle is drawnpartially around the captured clot.

FIG. 5C is a perspective view of a third alternative obstructivematter-capturing receptacle which may be incorporated into any of theembolectomy catheters of the present invention.

FIG. 6 is a perspective view of an optional guide catheter of thepresent invention having a proximal obstructive matter containmentapparatus operatively deployed therefrom, and an embolectomy catheter ofthe present invention operatively inserted therethrough.

FIG. 7 is an elevational view of a variant of the helical basket typeobstructive matter capturing receptacle of the catheters shown in FIGS.1, 2B and 4, such variant being constructed of metal ribbon rather thanwire.

FIG. 7A is a cross-sectional view through line 7A-7A of FIG. 7,illustrating the manner in which the metal ribbons may be twisted toenhance the ability of the proximal strut portions to the obstructivematter capturing receptacle to cut through the thromboembolic material.

FIGS. 8A-8F are step-wise showings of a procedure wherein the firstembodiment (i.e., an over-the-wire embodiment) of an embolectomycatheter of the present invention is used to remove a blood clot from asmall blood vessel of a mammalian body.

FIGS. 9A-9D are step-wise showings of a procedure wherein the thirdembodiment (i.e., a rapid exchange embodiment) of an embolectomycatheter of the present invention is used to remove a blood clot from asmall blood vessel of a mammalian body.

FIG. 10 is elevational view of an exemplary embodiment of anover-the-guidewire and embolectomy catheter of the present inventionincluding an exemplary operating handle and coiled storageconfiguration.

FIG. 11A is an elevational view of the operating handle of FIG. 10showing internal features in dashed line.

FIG. 11B is an isolated view of a sliding infusion port of the operatinghandle.

FIG. 11C is an end view of FIG. 11B.

FIG. 12 is an isolated view of the sliding infusion port with an outertube of the embolectomy catheter attached to the distal end.

FIG. 12A is a detailed view of the junction between the sliding infusionport and the catheter outer tube.

FIG. 12B is an end view of a threaded plug that inserts into theproximal end of the sliding infusion port.

FIG. 12C is a side view of the threaded plug of FIG. 12B.

FIG. 13 is a schematic view of outer tube of the embolectomy catheter ofthe present invention.

FIG. 14 is a schematic view of an inner tube of the embolectomy catheterof the present invention.

FIG. 15 is an elevational view of a proximal end of the catheter innertube, with a proximal guidewire introducer, an inner hypotube, and thesliding infusion port mounted thereon.

FIG. 15A is a detailed sectional view of the junction between the innerhypotube and the proximal end of the catheter inner tube.

FIGS. 16A-16E are various views showing the structure and sequence offabrication of the catheter inner tube.

FIG. 17A is an elevational view of the distal end of the catheter innertube and a length of distal tip tubing having a radiopaque band mountedthereon.

FIG. 17B is an elevational view similar to FIG. 17A and showing theattachment of clot removal wires and a second radiopaque band.

FIG. 18A is an elevational view of a tapered tube prior to formationinto a distal tip of the embolectomy catheter.

FIG. 18B is elevational view of the distal end of the catheter innertube, much like FIG. 17B, and showing the distal tip mounted thereon.

FIG. 18C is an elevational view of a fully assembled distal end of theembolectomy catheter, showing internal features in dashed line.

FIG. 19A is a sectional view through the fully assembled distal end ofthe embolectomy catheter.

FIG. 19B is a sectional view similar to FIG. 19A, but showing the clotremoval wires deployed to form a clot removal nest configuration.

FIG. 20A is elevational view of a fabrication tool for straightening theclot removal wires within the catheter outer tube.

FIG. 20B is a plan view of the fabrication tool of FIG. 20A.

FIG. 21A illustrates a guidewire of the present invention passingthrough a clot.

FIG. 21B illustrates a catheter of the present invention advancing overthe guidewire of FIG. 21A that has previously been partially or fullyadvanced through the clot.

FIG. 22 is a cross-section through a vessel showing the operation of aninfusion catheter of the present invention for clot removal.

FIG. 23A is a longitudinal cross-section through a vessel showing theoperation of an aspirating catheter of the present invention for clotremoval.

FIG. 23B is a transverse cross-section through the aspirating catheterof FIG. 23A.

FIG. 24A is a cross-section through a vessel showing the operation of aninfusion catheter of the present invention in combination with anocclusion balloon and a proximal clot capture device.

FIGS. 24B-24C are cross-sections through a vessel showing the operationof an infusion catheter of the present invention in combination withvarious distal clot capture devices.

FIG. 25A is a sectional view of the distal end of a catheter and aninfusion guidewire of the present invention passing therethrough.

FIG. 25B is a sectional view similar to FIG. 25A and showing an innerwire being retracted from the infusion guidewire.

FIGS. 26A-26D are longitudinal cross-sections through a vessel showingthe use of an infusion guidewire of the present invention.

FIGS. 27A-27D are longitudinal cross-sections through a vessel showingthe deployment of a clot removal device over the infusion guidewire ofthe present invention.

The particular embodiments shown in these drawings, and additionalembodiments of the invention, may now be better understood by readingand understanding the following detailed description wherein specificreference is made to the structures and steps illustrated or shown inthe drawings.

DETAILED DESCRIPTION OF THE INVENTION

A. Over-the Wire Embodiments of the Embolectomy Catheter Device:

Referring now to the drawings, wherein the showings are for the purposeof describing and illustrating exemplary embodiments of the presentinvention, and not for the purpose of limiting the scope of theinvention, FIG. 1 shows a human patient in whom an over the wireembodiment of the embolectomy catheter device 10 of the presentinvention has been inserted for the purpose of removing a thromboembolusor blood clot from a small artery located in the patient's brain. Priorto introduction of the catheter device 10 the offending clot was locatedby angiography or other imaging means, and a small guidewire GW (e.g., a0.010 in. Transend wire, Target/Boston Scientific catalog #46-802) wasinserted into the patients femoral artery and advanced into the arteryof the brain in which the clot is located, and through the clot.Thereafter, the catheter device 10 was advanced over the previouslyinserted guidewire GW to a position where the distal end of the catheterdevice 10 is near the clot. Alternatively, the guidewire is first placedinto the catheter before insertion into the patient, and the catheterand guidewire are advanced together as a unit up to and through theclot.

First Embodiment

As shown in FIGS. 1-2D, the first embodiment of the over-the-wirecatheter device 10 comprises an elongate, pliable catheter 11 having aclot capturing receptacle 14 deployable from its distal end DE, asshown. The obstructive matter-capturing receptacle 14 is formed of aplurality (e.g., 2 or more) wire members 20 which are initiallyretractable to substantially straight configurations and a first (i.e.,stowed) position, within the catheter 11. (See FIG. 2A) When it isdesired to deploy the obstructive matter capturing receptacle 14, thepreformed wire members 20 are held stationary while the catheter 11 isretracted, or the wire members 20 are advanced in the distal directionwhile holding the catheter 11 stationary, such that the wires emergefrom the constraint of the catheter 11 and resiliently assume a second(i.e. operative) configuration wherein the distal portions of the wiremembers form a helical basket 16 having an open proximal mouth or rim17, as shown in FIG. 2B. When in such operative configuration (FIG. 2B),the helical basket 16 is sufficiently porous to allow blood to flowtherethrough, but sufficiently dense to engage and withdraw in theproximal direction, a thromboembolism. A nose cone 30 is positioned onthe distal ends of the wire members 18. The proximal portions 18 of theelongate wire members 20 act as connecting members between the helicalbasket 16 and the catheter 11. These proximal portions 18 of the wiremembers 20 are of sufficiently small diameter or are otherwiseconfigured to be retracted through a thromboembolism, without causingsubstantial disruption or segmentation of the thromboembolism. In someembodiments energy (e.g. heat, vibration, etc) may be applied to theproximal portions 18 of the wire members 20 to facilitate theirretraction through the thromboembolic material without causingsubstantial disruption or segmentation of the thromboembolism.

The wire members 20 of which the capturing receptacle 14 is formed maybe of any suitable material, such as elastic, superelastic or shapememory alloy wire. The distal portions of these wire members arepreformed to the shape of the helical basket 16 but are sufficientlyelastic to assume substantially straight configurations when retractedthrough the guide bores 26 and into the catheter 11 and maintained in ataut state under a small amount of proximally directed pressure. (SeeFIG. 2A) However, when these preformed wire members are extended oradvanced through the guide bores 26 and out of the distal end DE of thecatheter 11, and relieved of the surrounding restraint of the catheter11 and the proximally-directed tension, they will resiliently self-coilinto the generally frustoconical shape of the helical basket 16.

To facilitate the desired advancement and retraction of these preformedwire members 20, the proximal ends of these members 20 are attached tothe distal end of a longitudinally slideable actuator 24 which ispositioned within the lumen 22 of the catheter body 12. A hollowactuator lumen 22 a extends through the actuator 24 and is in axialalignment with the lumen 22 of the catheter body 12. The shaft of theactuator 24 has a wire braid 25 formed therein to impart stiffness andstrength. A distal tip member 28 is formed on the distal end DE of thecatheter body 12, such distal tip member 28 having a hollow tip memberlumen 22TM which extends longitudinally through the center thereof, andfour (4) wire passage bores 26 which also extending longitudinallytherethrough, at radially spaced-apart locations (i.e., the 3, 6, 9 and12 o'clock positions). The distal tip member 28 may be formed ofmaterial which is more rigid than the catheter body 12 and may have aproximal portion 40 of reduced diameter which is inserted into thedistal end DE of the catheter body lumen 22, as shown in FIGS. 2A, 2Band 2D. Each of the four (4) preformed segments 20 which form theobstructive matter capturing receptacle 14, when advanced out of thecatheter 11 must pass through a respective one of the wire passage bores26 formed in the catheter tip member 28. FIG. 2D′ shows an alternativeconstruction of the distal tip member wherein four (4) cut-out notches26 alt are formed at the 3, 6, 9 and 12 o'clock positions to serve asdiscrete guide wire passageways for the individual wire segments 20, inlieu of the wire passage bores 26.

As seen in FIG. 1, a proximal actuator shaft 24′ attached to theactuator 24 extends to a housing 13 formed on the proximal end of thecatheter. The proximal actuator shaft 24′ may be manually advanced andretracted to control deployment and retraction of the obstructive mattercapturing receptacle 14. A contrast medium injection port 15 is alsoformed on the proximal housing 13, for injection of radiographiccontrast medium through the lumen 22 and out of the distal end DE of thecatheter 11. In this regard, it is preferable that the outer diameter ofthe guidewire GW be at least slightly less than the inner diameter ofthe lumen 22 to permit some radiographic contrast medium to pass throughthe lumen 22 and out of the distal end of the catheter even when theguidewire is positioned within the lumen. Also, radiographic contrastsolutions (i.e., dyes) of minimal viscosity may be selected to enhancethe ability of the contrast medium to pass through the lumen 22 whilethe guidewire GW is positioned therewithin.

When the actuator 24 is withdrawn in the proximal direction, it willpull the wire segments 20 in the proximal direction, through the wirepassage bores 26 and into the lumen 22 of the catheter. When theactuator 24 is fully retracted, as shown in FIG. 2A, the segments 20will be drawn fully through the wire passage bores 26 and will assumesubstantially straight configurations, and the nose cone 30 mounted onthe distal end of the obstructive matter capturing receptacle will be indirect abutment with the catheter tip member 28 such that the hollownose cone lumen 22NC is in axial alignment with the distal tip lumen22DT and the lumen 22 of the catheter body 12.

Second Embodiment

FIGS. 3B and 3B′ show a second embodiment of an over-the-wire catheterdevice 10′ which differs from the first embodiment 10 in several ways.For example, the obstructive matter-capturing receptacle (not shown) ofthis second embodiment is formed by only two (2) wire members 20′instead of four (4) as in the first embodiment 10. Also, the catheter11′ of this second embodiment incorporates an elongate distal segment270 of reduced diameter and increased flexibility--similar to that ofthe commercially available microcatheters (e.g., Prowler™ microcatheter,Cordis Endovascular Systems, Miami Lakes, Fla.), an example of which isshown in FIG. 3A and generally comprises a proximal portion PP having alumen L and a distal segment 270 having a lumen 271 which is continuouswith the lumen L of the proximal portion PP.

With specific reference to FIGS. 3B and 3B′, this second embodiment ofthe over the wire embolectomy catheter device 10′ comprises an elongate,pliable catheter 11′ having a helical basket type obstructive mattercapturing receptacle (not shown)similar to that of the first embodiment,but wherein the receptacle (not shown) is formed of only two (2) wiremembers. As in the above described first embodiment, the obstructivematter capturing receptacle (not shown) of this second embodiment 10′ isinitially retractable to a first (i.e., stowed) configuration and issubsequently advanceable to second (i.e. operative) configuration whichis essentially the same as that described above with respect to thefirst embodiment 10.

In this second embodiment, the flexible catheter 11′ comprises aproximal portion 12′ having a first diameter and first flexibility, anda distal portion 270 which has a second (i.e., smaller) diameter and asecond (i.e., greater) flexibility. An insert member 28′ having four (4)guide bores 26′ extending longitudinally therethrough, is positionedwithin the lumen 271′ of, and is coextensive with, the distal portion270 of the catheter 11′. This insert member 28′ is a generallycylindrical member having four (4) longitudinal bores 20′ extendingtherethrough, as shown in FIG. 3B′. However, since the obstructivematter capturing receptacle (not shown) of this embodiment is formed ofonly two (2) elongate members 20′, the remaining two guide bores 26′remain unoccupied and may serve as passageways through whichradiographic contrast medium (e.g., dye), medicaments, perfusionsolution or other fluid my flow.

B. Rapid Exchange Embodiments of the Embolectomy Catheter Device:

FIGS. 3D, 3D′, 3E, 3E′, 3F′, 3F′ and 4 are illustrative of rapidexchange embodiments of the embolectomy catheter device 10″, 10′″ and10″″. These rapid exchange embolectomy catheter devices 10″, 10′″ and10″″ incorporate guidewire lumens which extend through only a distalportion of the catheter 11″, 11′″, 11″″ so as to permit the catheter11″, 11′″, 11″″ to be exchanged without the need for use of anexchange-length guidewire (i.e., a guidewire which is long enough toallow the exteriorized portion of the guidewire to be longer than thecatheter so that the catheter may be withdrawn, removed and exchangedwhile holding the guidewire in substantially fixed position. Theserapid-exchange embodiments are particularly suited for the treatment ofstroke by removing thromboemboli from small blood vessels of the brain(i.e., blood vessels located on, in or around the brain), as the use ofexchange-length guidewires may be undesirable in such delicateneuroradiological procedures. see, Morris, P., Practical Neuroradiology,Chapter 2, page 41 (Williams & Wilkins 1997)

Third Embodiment

FIGS. 3D and 3D′ show a third embodiment (i.e., a rapid exchange typeembodiment) of the embolectomy catheter device 10″ which is similar inconstruction to the above described second embodiment 10′, but whichincorporates a guidewire passage port 267′ formed in the sidewall of thecatheter 11″ near the distal end of its proximal portion 12′, and aguidewire deflector tube 260′ which extends from the guidewire passageport 267′ to the lumen 22′. The guidewire deflector tube 260′ has aflared distal end which is held in a centered position within the lumenby a plurality of radial support members 264′. Longitudinal passages266, 266(alt) are formed between the radial support members 264′ toallow radiographic contrast medium or other fluid to flow through thelumen 22′, past the flared distal end of the guidewire deflector tube260′. Selected ones of the longitudinal passages 266(alt) are largerthan the others 266 to permit the elongate members 20′ which form theobstructive matter capturing receptacle to pass therethrough, as shown.The proximal end of a guidewire PEG may be inserted into the distal endopening DEO of the catheter 11″ and, thereafter, the catheter 11″ may beadvanced in the distal direction such that the proximal end of theguidewire PEG will enter the flared distal end of the guidewiredeflector tube 260′, and will be thereby deflected out of the sideguidewire passage port 267′, as shown.

Fourth Embodiment

In the fourth embodiment (i.e., another rapid exchange embodiment) shownin FIGS. 3E and 3E′, the catheter 11′″ comprises a main tube 300 whichhas a proximal portion 302 of a first diameter D1 and a distal portion304 of a second diameter D2. A side tube 308 is affixed to one side ofthe distal portion 304 of the main tube 300, and a guidewire passageaperture 310 is formed into the lumen 309 of the side tube 308, suchthat the lumen 309 of the side tube may be used as the guidewire lumen,and the distal portion of the guidewire GW which emerges from the sidetube lumen 309 may then be passed through the separate guidewire lumenof the obstructive matter capturing receptacle 22 (not shown in FIG. 3E)and/or any nose cone lumen 22NC (not shown in FIG. 3E), as describedfully hereabove.

Fifth Embodiment

The fifth embodiment (i.e., another rapid exchange embodiment) of theembolectomy catheter device 10″″ is similar in construction and operatesin the same manner as the fourth embodiment 10′″ described above, exceptthat the main tube 300′ of this fifth embodiment 10″″ is formed of acontinuous wire 316 which is would in a tight helical coil, as shown.This construction of the main tube 300′ may provide enhanced flexibilityover other forms of construction.

C. Alternative Components and Optional Elements Which May beIncorporated into any Embodiment of the Embolectomy Catheter Devices:

I. Alternative Types of Obstructive matter Capturing Receptacles:

The embolectomy catheter devices 10, 10′, 10″, 10′″, 10″″ of the presentinvention may incorporate various types of obstructive matter capturingreceptacles as alternatives to the helical wire basket type receptacles14, 14′ shown in FIGS. 1A, 2B and 4. In particular, several alternativeobstructive matter capturing receptacles are shown in FIGS. 5-7.

FIGS. 5-5A show one alternative obstructive matter-capturing receptacle400 which comprises a plurality of elastic or superelastic wire spokes402 which are preformed to a radially splayed configuration as shown,and which have a membranous or fabric cover 404 disposed thereon to forman umbrella like structure. The membranous or fabric cover 404 may be ofnon-porous or porous configuration, and is preferably formed of materialsuch as polyethylene, polytetrafluoroethylene, polyurethane, ethylenevinyl acetate or silicone. A central hub is formed at the center of thespokes 402, and a guidewire lumen extends through such central hub suchthat the guidewire may pass the center of the receptacle 400, in themanner depicted in FIGS. 5 and 5A. The ends of the spokes 402 may havebulbs 408 formed thereon to minimize trauma to the surrounding bloodvessel walls, as shown in FIG. 5′. Or, as an alternative to such bulbs408, atraumatic loops 410 may be formed on the distal ends of the spokes402 to prevent vascular trauma. The spokes 402 are of sufficiently smalldiameter to be retracted through a thromboembolism without causingsubstantial disruption of segmentation of the thromboembolism.

FIGS. 5B-5B″ show another obstructive matter capturing receptacle 420which comprises a plurality of elastic or superelastic wire spokes 402′which are pre-formed to a radially splayed configuration as shown, and aporous fabric (e.g., woven, knitted, mesh or net fabric) sac 422attached to the spokes 402′ to form an umbrella-like structure, asshown. The material used to form this sac 422 may be the samemicroporous material as specified hereabove with respect to themembranous or fabric cover 404 of the embodiment shown in FIG. 5. Acentral aperture 426 is formed in the sac 422 such that a guidewire GWmay be passed through a region among the spokes 402′, and through suchaperture 426, as shown in FIGS. 5B and 5B′. Draw lines 424 are attachedto the free ends of the spokes 402′ and extend through the lumen of thecatheter. These draw lines 424 and the spokes 402′ are of sufficientlysmall diameter to be retracted through a thromboembolism without causingsubstantial disruption or segmentation of the thromboembolism. After thereceptacle 420 has been advanced through the thromboembolism, it isdeployed (e.g., radially expanded) and retracted such that the drawlines 424 and spokes 402′ will retract through and will become locatedproximal to, the thromboembolism. Thereafter, the draw lines 424 areretractable into the catheter to pull distal ends of the spokes 402′inwardly such that the proximal mouth PM of the sac will be drawnpartially around the captured obstructive matter in the manner shown inFIGS. 5B′ and 5B″.

FIG. 5C shows another alternative obstructive matter capturingreceptacle which employs a resilient, generally football shaped cage toeffect radial expansion/contraction of a membranous or fabric cover 444.As shown, the cage comprises approximately six (6) elongate members 442of preformed elastic, super-elastic or shape memory metal wire disposedlongitudinally about a longitudinal axis LA, and having the membranousor fabric covering 444 disposed on the distal portions DP thereof. Thedistal ends DE of the elongate members 442 are attached to a nose cone446 which has a guidewire passage lumen extending longitudinallytherethrough. When retracted into the lumen of the catheter, the members442 will radially compress to a diameter which is received within thecatheter lumen. However, when advanced out of the catheter the members442 will resiliently expand to the configuration shown. The proximalportions of the members are sufficiently small in diameter to slice, cutor otherwise pass in the proximal direction through a thromboembolism orclot without disrupting or causing fragmentation of the thromboembolismor clot.

FIGS. 7 and 7A show an alternative helical basket type of obstructivematter capturing receptacle 14″ which is of the same generalconfiguration, and operates in the same manner, as the helical baskettype receptacles 14,14′ shown in FIGS. 1A and 4, but wherein thereceptacle 14″ is formed of a plurality of flat ribbons 500 formed ofmetal such as Elgiloy™ cobalt-chromium-nickel alloy (Elgiloy, Inc.,Elgin, Ill.) or suitable resilient plastic. The distal portions of theflat ribbons 500 are preformed to helical configurations to form thehelical basket 502. The proximal portions of the ribbons 500 serve asconnector members 504 between the helical basket 502 and the catheter11. Each ribbon 500 has first and second flat surfaces 512 and first andsecond edges 514. Each of the ribbons 500 is twisted 90 degrees at apoint of transition 510 between the connector members 504 and thehelical basket 502. This twisting of the ribbons causes a) the distalportions to be situated with their edges 514 in juxtaposition such thata thromboembolus contained within the helical basket 502 will rest uponthe flat surfaces of the ribbons 500, and b) the proximal portions to besituated with their edges aimed in the proximal direction to facilitateretraction of the distal connector members 504 through thethromboembolus without causing the thromboembolus to be substantiallyfragmented or disrupted.

Optional Guide Catheter/Proximal Obstructive Matter Retaining Member:

As illustrated in FIG. 6, it may be desirable to use the embolectomycatheter devices 10, 10′, 10″, 10′″, 10″″ in conjunction with a guidecatheter 50 through which the embolectomy catheter 11 may be advanced.When such guide catheter 50 is used, a proximal obstructive matterretaining member 52, such as a tubular sheath having a radially flaredand splayable distal end as shown in FIG. 5A, may be advanced out of thedistal end DE of the guide catheter 50 such that the clot C or otherobstructive matter may be captured between the distal obstructive matterreceiving portion 16 of the receptacle 14 and the flared distal end ofthe proximal obstructive matter retaining member 52. The use of thisoptional proximal obstructive matter retaining member 52 may beparticularly useful in cases where the thromboembolism is very fresh orhas been inadvertently severed or segmented so as to present a danger ofbreaking apart or fragmenting during the removal procedure.

D. Rapid Exchange Microcatheter Useable in Conjunction with theEmbolectomy Catheters:

In many procedures wherein the embolectomy catheters of this inventionare used to remove thromboemboli from small blood vessels of the brain,it will be desirable to initially perform an angiogram of the bloodvessel wherein the thromboembolism is believed to be located to a)verify the exact location of the thromboembolism and b) radiographicallymap the vascular anatomy in the immediate area of the thromboembolismand c) guide and verify the passage of a small guidewire through theoffending thromboembolism. Because the embolectomy catheters 10, 10′,10″, 10′″, 10″″ of the present invention may necessarily be of verysmall diameter (e.g., 0.10-0.20 inches) in order to navigate the tinyblood vessels of the brain, the presence of the retracted obstructivematter capturing receptacle 14, 14′, 400, 420 or 440 within thatcatheter 11 may severely limit the amount of radiographic contrastmedium which could be infused though that catheter 11. Thus, in manyinstances, it may be desirable to initially insert a small angiographycatheter (e.g., a microcatheter such as the Prowler™ microcatheter,Cordis Endovascular Systems, Miami Lakes, Fla.), an example of which isshown in FIG. 3A, into the obstructed blood vessel to perform theinitial angiography and to accomplish precise positioning of theguidewire through the thromboembolism. After the initial angiography hasbeen performed and the guidewire has been precisely positioned, theangiography catheter is withdrawn and removed, leaving the guidewire inplace. Thereafter, an embolectomy catheter 10, 10′, 10″, 10′″, 10″″ ofthe present invention is advanced over the pre-positioned guidewire tothe location of the thromboembolism.

However, the microcatheters of the prior art have not been suitablydesigned for this novel procedure. Such microcatheters have heretoforeof an “over-the-wire” type used primarily in procedures where thecatheter is retracted and removed concurrently with the guidewire overwhich it was inserted. Thus, as those skilled in the art willappreciate, the prior art “over-the-wire” type microcatheters can onlybe exchanged over a stationary guidewire if the guidewire is an“exchange-length” wire or if an extension has been attached to theproximal end of the guidewire to permit the exchange. However, the useof such “exchange-length” guidewire or a guidewire extension may becontraindicated in procedures where the catheters are being insertedinto and withdrawn from tiny delicate vessels of the brain. see, Morris,P., Practical Neuroradiology, Chapter 2, page 41 (Williams & Wilkins1997)

In view of this shortcoming of the prior art microcatheters, applicanthas devised the rapid-exchange microcatheter 265 shown in FIGS. 3C and3C′. This rapid exchange microcatheter 265 comprises an elongate,flexible catheter having a proximal portion 12″ of a first diameter andfirst flexibility, and a distal portion 270″ which has a second (i.e.,smaller) diameter and a second (i.e., greater) flexibility.

A guidewire passage port 267 is formed in the sidewall of the catheternear the distal end of its proximal portion 12″, and a guidewiredeflector tube 260 extends from the guidewire passage port 267 to thelumen 271. The guidewire deflector tube 260 has a flared distal endwhich is held in a centered position within the lumen by a plurality ofradial support members 264. Longitudinal passages 266 are formed betweenthe radial support members 264 to allow radiographic contrast medium orother fluid to flow through the lumen 271, past the flared distal end ofthe guidewire deflector tube 260. The proximal end of a guidewire PEGmay be inserted into the distal end opening DEO of the catheter and,thereafter, the catheter may be advanced in the distal direction suchthat the proximal end of the guidewire PEG will enter the flared distalend of the guidewire deflector tube 260, and will be thereby deflectedout of the side guidewire passage port 267, as shown in FIG. 3C.

E. Methods for Using the Invention to Remove Clots or Other ObstructiveMatter from Blood Vessels:

FIGS. 8A-8F illustrate an exemplary method of using an the over-the-wiretype embolectomy catheter 10 of the invention to remove a obstructivematter such as a thromboembolism or blood clot, while FIGS. 9A-9Cillustrate an exemplary method of using a rapid exchange typeembolectomy catheter 10″ of the invention to remove such obstructivematter. These exemplary procedures are described in detail in theparagraphs below.

Exemplary Use of the Over-the-Wire Embolectomy Catheter

FIGS. 8A-8F show an exemplary method for using the over-the-wire typeembolectomy catheter 10 shown in FIGS. 1 -2D to remove a thromboembolusor clot C which has become lodged immediately downstream of an arterialbifurcation BE so as to create an ischemic zone IZ of tissue (e.g.,brain tissue which is deprived of oxygen and other nutrients) locateddownstream of the clot C. The exemplary procedures depicted in thesedrawings are described in the paragraphs herebelow.

Initially, a microcatheter such as the rapid exchange microcatheter 265of FIG. 3C (not shown in FIGS. 8A-8F) is advanced to a position near theobstructive matter or clot C and radiographic contrast medium isinjected through the microcatheter to angiographically verify theprecise location of the clot C and to visualize or map the anatomy ofthe blood vessels in the area of the clot. Thereafter, a guidewirehaving a diameter of 0.01-0.014 inches and a length which is not morethan 1.5 times the length of the microcatheter 265 (i.e., not an“exchange-length” guidewire) is advanced from the lumen 271 of themicrocatheter 265 until its distal tip DT has passed through the clot Cas shown in FIG. 8A.

Thereafter, the operator will hold the proximal end of the guidewire GWto prevent longitudinal retraction of the guidewire GW while retractingand removing the rapid exchange microcatheter 265. This allows theguidewire GW to remain in its operative position as shown in FIG. 8A.

Thereafter, as shown in FIG. 8B, the embolectomy catheter 11 having itsobstructive matter capturing receptacle retracted to its firstconfiguration (FIG. 2A) is advanced over the guidewire GW and throughthe clot C, such that the distal end opening DEO of the catheter 11 islocated downstream of the clot C but still proximal to (i.e., upstreamof) the distal tip DT of the guidewire GW.

Thereafter, as shown in FIGS. 8C and 8 d, the actuator 28 is advanced inthe distal direction to cause the four wire segments 20 which form theobstructive matter capturing receptacle 14 to advance out of the distalend of the catheter such that the nose cone 30 remains upon theguidewire GW. In this manner, the obstructive matter capturingreceptacle 14 is fully deployed to its second or operative configurationat a location distal to (i.e., downstream of) the clot C (FIG. 3D).

Thereafter, as shown in FIG. 8E, the embolectomy catheter 11 isretracted in the proximal direction to cause the proximal connectormembers 18 of the obstructive matter capturing receptacle 14 to passthrough the clot, and to further cause the clot to be received withinthe concave or cavernous interior of the distal obstructive matterreceiving portion 16 of the receptacle 14, as shown.

Thereafter, as shown in FIG. 8F, the entire embolectomy catheter device10, with the clot C in tow, may be retracted out of the body—or to alocation within a larger blood vessel (e.g., a jugular vein or the venacave) where the clot C and the fully deployed obstructive mattercapturing receptacle 14 may be received within the lumen of a largercatheter to further secure the clot for ultimate extraction and removalform the body.

Exemplary Use of the Rapid Exchange Embolectomy Catheter

The exemplary method of using a rapid exchange type embolectomy catheterof this invention 10″ is shown in FIGS. 9A-9D.

Initially, a microcatheter such as the rapid exchange microcatheter 265of FIG. 3C (not shown in FIGS. 9A-9D) is advanced to a position near theclot C and radiographic contrast medium is injected through themicrocatheter to angiographically verify the precise location of theclot C and to visualize or map the anatomy of the blood vessels in thearea of the clot. Thereafter, a guidewire having a diameter of0.006-0.018 inches and a length which is not more than 1.5 times thelength of the microcatheter 265 (i.e., not an “exchange-length”guidewire) is advanced from the lumen 271 of the microcatheter 265 untilits distal tip DT has passed through the clot C as shown in FIG. 9A.

Thereafter, the operator will hold the proximal end of the guidewire GWto prevent longitudinal retraction of the guidewire GW while retractingand removing the rapid exchange microcatheter 265. This allows theguidewire GW to remain in its operative position as shown in FIG. 9A.

Thereafter, as shown in FIG. 9B, the exteriorized proximal end of theguidewire is inserted into the distal end opening DEO of the rapidexchange embolectomy catheter 11″ while its obstructive matter capturingreceptacle is retracted to its first configuration (FIG. 2A) within thedistal portion of the catheter 11″. As the catheter is advanced in thedistal direction over the guidewire GW, the guidewire will be deflectedby the guidewire deflection tube 260′ (see FIG. 3D) and the proximal endof the guidewire will emerge out of the side guidewire passage aperture267′ of the catheter 11″. The catheter 11″ is advanced through the clotC, such that the distal end opening DEO of the catheter 11″ is locateddownstream of the clot C but still proximal to (i.e., upstream of) thedistal tip DT of the guidewire GW, as shown in FIG. 9C. The guidewire GWextends along side of the proximal portion of the rapid exchangecatheter 11 ″ (i.e., the portion of the catheter proximal to theguidewire passage aperture 267′), as shown.

Thereafter, as shown in FIG. 9D, the actuator 28 is advanced in thedistal direction to cause the two (2) wire members 20′ which form theobstructive matter capturing receptacle 14′ to advance out of the distalend of the catheter 11′ such that the nose cone 30′ remains upon theguidewire GW. In this manner, the obstructive matter capturingreceptacle 14′ is fully deployed to its second or operativeconfiguration at a location distal to (i.e., downstream of) the clot C(FIG. 9D).

Thereafter, the rapid exchange embolectomy catheter 11′ is retracted inthe proximal direction to cause the proximal connector members 18′ ofthe obstructive matter capturing receptacle 14′ to pass through theclot, and to further cause the clot to be received within the concave orcavernous interior of the helical basket 16′ of the receptacle 14′. Theclot C is then removed by retraction of the catheter 11′, in the samemanner shown and described above and shown in FIGS. 8E and 8F.

Exemplary Embolectomy Catheter

FIGS. 10-19 illustrate various aspects of an exemplary “over-the-wire”embolectomy catheter 600 of the present invention that utilizes a nestedwire type of clot capture device. The embolectomy catheter 600 is seenin FIG. 10 in its entirety, and as it would appear in its shippingpackage. The embolectomy catheter 600 comprises an operating handle 602,a guidewire 604, and an insertion portion (608 in FIG. 11A) that ishidden by a storage coil 606. The storage coil 606 comprises a flexiblelength of tubing to protect the insertion portion 608, and is held inits coiled configuration by a plurality of brackets 610.

FIG. 11A illustrates the embolectomy catheter 600 removed from thestorage coil 606 of FIG. 10. The insertion portion 608 is shown on theright, or distal side, in broken line to enable visualization of itsentire length. More specifically, the insertion portion 608 has a lengthL_(c) from the handle 60 to a distal end 611 of approximately 59 inchesto enable access to distant reaches of a patient'vasculature through anaccess incision in the femoral artery, for example.

The operating handle 602 includes a rigid handle body 612 having aproximal end 614 and a tapered distal end 616. An elongate channel 618opening upward as seen in FIG. 11A extends substantially the entirelength of the handle body 612. Throughbores on either end of the channel618 provide passages for elements of the embolectomy catheter 600. Inparticular, a throughbore on the proximal end 614 receives a guidewireintroducer 620 having a tapered configuration. A bore 621 of theguidewire introducer 620 sealingly mates with an inner hypotube 622 asindicated at 624. The hypotube 622 continues in a distal direction tomate with an inner tube of the insertion portion 608, as will be morefully described below. A strain relief nose 626 and a strain relief tube628 are fastened to the tapered distal end 616 of handle body 612. Thesetwo strain relief elements 626, 628 prevent damage to the insertionportion 608 from excessive bending as it passes out of the through borein the distal end 616.

With reference now to FIGS. 11A-11C, a sliding infusion port 630 ismounted for linear translation within the channel 618. The slidinginfusion port 630, as seen in FIG. 11B, includes a slide portion 632having a width w_(s), and a height h_(s) so as to closely fit within thechannel 618. In an exemplary embodiment, the height h_(s) is slightlygreater than the width w_(s); for example, the height h_(s) may be about0.25 inches and the width w_(s) may be about 0.24 inches. In the sameexample, the slide portion 632 has a length I_(s) of about 1.08 inches.A through bore 634 extends from one end of the slide portion 632 to theother. A side tube 636 projects upward at an angle of about 30 degreesfrom the slide portion 632, and is supported by a web 638. The side tube636 terminates in an infusion port 640, and a side lumen 642 definedtherewithin intercepts the through bore 634 near the distal end of theslide portion 632. A circular shaft journal 644 is provided in the web638. As will be explained more fully below, the sliding infusion port630 is fixedly mounted with respect to an outer tube of the insertionportion 608 and causes the outer tube to translate with respect to aninner tube.

With reference again to FIG. 11A, a mechanism for regulating motion ofthe sliding infusion port 630 includes a thumb-wheel tightening bolt 646mounted for rotation within the shaft journal 644, and a carriage 648.The carriage 648 surrounds the handle body 612 and maintains the slidinginfusion port 630 within the channel 618. Although not shown in detail,the thumb-wheel tightening bolt 646 is configured to clamp the slideinfusion port 630 with respect to the handle body 612 to preventmovement therebetween. In this manner, the thumb-wheel tightening bolt646 is first loosened and then the sliding infusion port 630 is manuallyslid along the channel 618. The thumb-wheel tightening bolt 646 isuseful to maintain the catheter iun an undeployed configuration duringpackaging and shipment. At the desired position, the thumb-wheeltightening bolt 646 may be tightened to lock the slide infusion port 630in place. Alternatively, the thumb-wheel tightening bolt 646 may beconfigured to actually move the sliding infusion port 630 and carriage648 linearly along the handle body 612. For example, the actuating wheel646 could have gear teeth that mesh with teeth on a rack provided on thehandle body 612. Alternatively, the thumb-wheel tightening bolt 646 mayhave an elastomeric sleeve made of a material with a high coefficient offriction that frictionally engages a surface of the handle body 612.Whatever the interface between the thumb-wheel tightening bolt 646 andhandle body 612, those of skill in the art will understand that avariety of mechanisms can be provided for displacing the slidinginfusion port 630 within the channel 618 and fastening it at variouslocations.

FIGS. 12 and 12A-12C illustrate the sliding infusion port 630 in greaterdetail with additional components connected thereto. More specifically,a catheter outer tube 650 attaches to and projects distally from adistal end of the slide portion 632. A detail of the interface betweenthe slide portion 632 and the catheter outer tube 650 is seen in FIG.12A. A rigid, preferably metal, tubular sleeve 652 is fastened at thedistal end of the through bore 634, and has an outer hypotube 654extending distally therefrom. The catheter outer tube 650 has a lumen656 that is flared or stepped slightly larger in size at a proximal endto overlap the outer hypotube 654 in the region 658. The catheter outertube 650 terminates short of the slide portion 632 by a gap G_(o) whichis, at most, 0.1 inches. An adhesive or other suitable bonding compound660 is provided in this gap G_(o), and in the annular space between thehypotube 654 and catheter outer tube 650. The sleeve 652 includes alumen 662 that is sized the same as the lumen of the hypotube 654, andthe lumen 656 of the catheter outer tube 650. Consequently, and as willbe clear from the description below, the inner hypotube 622 (shown inphantom) passes easily through these co-linear lumens without fictionalinterference from steps or other such narrowing.

FIGS. 12B and 12C illustrate a threaded plug 664 that fits within athreaded distal portion of the throughbore 634. The threaded plug 664holds a pair of seals 666 within the through bore 634. The seals 666have bore diameters that provide a sliding seal around the innerhypotube 622. By virtue of the seals 666, fluid introduced through theinfusion port 640, the side lumen 642, into the through bore 634 isprevented from passing proximally from the throughbore. Instead, thefluid passes through an annular gap between the sleeve lumen 662 and theinner hypotube 622, and then travels distally through the catheterinsertion portion 608.

Now with reference to FIGS. 13 and 14, inner and outer telescoping tubesof the catheter insertion portion 608 will be described. FIGS. 13illustrates the catheter outer tube 650 extending from the strain relieftube 628 to a distal end 670. The outer tube 650 comprises a reinforcedproximal segment 672, an un-reinforced middle segment 674, and a distalsheath 676 attached in series at 677 to the un-reinforced segment andextending to the distal end 670. The various lengths of these segmentsare given as: L_(o) is the length of the outer tube 650, L_(op) is thelength of the proximal segment 672, L_(om) is the length of the middlesegment 674, and L_(od) is the length of the distal sheath 676. In anexemplary embodiment, L_(o) equals about 59 inches, L_(op) equals about52 inches, L_(om) equals about 5 inches, and L_(od) equals about 2inches.

The catheter outer tube 650 is constructed with higher strength andlower flexibility at its proximal end, and gradually becomes moreflexible and consequently less strong in the distal direction. Theproximal segment 672 is desirably made of a polymer reinforced withhelically wound wires or other suitable means. For example, the polymermay be polyether block amide, sold under the trade name PEBAX, and thereinforcements may be 16 stainless-steel wires arranged in a helicalarray. The middle segment 674 is desirably an un-reinforced polymer,such as polyurethane. Finally, the distal sheath 676 is a relativelythin polymer tube, preferably PEBAX.

A portion of a reinforced catheter inner tube 680 is seen in FIG. 14,and includes a proximal reinforced segment 682 and a distalun-reinforced segment 684. Along the insertion portion 608 (FIG. 11A),the length of the reinforced inner tube 680 is approximately equal tothe length of the catheter outer tube 650. The length L_(ip) of theproximal reinforced segment 682 may be about 32 inches, while lengthL_(id) of the distal un-reinforced segment 684 is about 27 inches.

The reinforced catheter inner tube 680 comprises an inner tube 686, areinforcing sleeve 688 surrounding a proximal segment of the inner tube686, and a distal segment 690 extending distally from the inner tube ata transition region 692. The inner tube 686 and attached distal segment690 extend the entire length of the reinforced inner tube 680, while thereinforcing sleeve 688 terminates slightly past the midpoint thereof,closer to the distal end. The reinforcing sleeve 688 is desirably apolymer shrink tube closely fitting around the inner tube 686. As withthe catheter outer tube 650, the reinforced inner tube 680 becomes moreflexible and less strong moving in the distal direction. The lengthL_(i12) of the inner tube 686 is desirably between about 55 inches,while the length L_(i4) of the distal segment 690 is desirably betweenabout 1-6 inches, and in a specific embodiment for treating ischemicstroke is about 4 inches.

The inner tube 686 is desirably made of a polymer tube reinforced withhelically wound wires, or the like. For example, the inner tube 686 maybe a PEBAX tube reinforced with 12 stainless-steel wires. Finally, thedistal segment 690 is also preferably reinforced, but to a lesser extentthan the inner tube 686. Therefore, the distal segment 690 may be, forexample, a tube of PEBAX reinforced with 4 stainless steel wires. Thisconstruction is seen in greater detail in FIGS. 16A-16D. It can thus beappreciated that the distal segment 690 may be a continuation of innertube 686, with some of the reinforcing wires removed. That is, forexample, the inner tubes 686 may be reinforced with an array of 12 wireswrapped helically therearound, and the distal segment 690 has only 4wires wrapped helically therearound resulting from simply removing 8 ofthe reinforcing wires in the area of the distal segment 690.

With reference now to FIGS. 15 and 15A, the proximal end of the elementsmaking up an inner lumen of the embolectomy catheter 600 is seen. FIG.15 shows the operating handle body 612 in phantom to better illustratethe interaction between the guidewire introducer 620, the inner hypotube622, the sliding infusion port 630, and the reinforced inner tube 680,all previously described. The catheter outer tube 650, as detailed inFIGS. 12 and 12A, is removed in FIG. 15 so that a junction between theinner hypotube 622 and the reinforced inner tube 680 can be seen, andfurther detailed in FIG. 15A.

As mentioned previously, the sliding infusion port 630 can be displacedwithin the channel 618 in the handle body 612, and rides over the innerhypotube 622. In this regard, the seals 666 held in by the threaded plug664 maintained a fluid-tight seal between the through bore 634 of thesliding infusion port 630, and inner hypotube 622. Again, this slidingseal ensures that fluid introduced through the infusion port 640 travelsin a distal direction between the catheter outer tube 650, andreinforced inner tube 680. Although not shown in FIG. 15, the readerwill appreciate that upon displacement of the sliding infusion port 630,the connected catheter outer tube 650 (see FIG. 12) also travelstelescopically over the inner hypotube 622, and over the reinforcedinner tube 680.

As detailed in FIG. 15A, the inner hypotube 622 connects in series withthe reinforced inner tube 680 using a junction sleeve 694 and adhesive696 or other suitable bonding compound. That is, the inner hypotube 622exhibits a reduction in diameter at a step 698, which reduction issufficient to permit the inner hypotube to fit within the inner tube 686in an overlap region 700. A gap G_(i) of approximately 0.05 inches isprovided between the proximal end of the inner tube 686 and the step698. The junction sleeve 694 is preferably a shrink tube that fitsclosely around the inner hypotube 622 just proximal to the step 698, andextends around the proximal end of the reinforcing sleeve 688. It shouldbe noted that the sleeves 688 and 694 are desirably shrink tubes, andthe gaps seen in the drawings are only for illustration purposes, andwould not be present in the actual catheter 600.

The junction sleeve 694 helps ensure no leakage into or out of acontinuous inner lumen 702 formed along the length of the inner hypotube622 and inner tube 686. In addition, the junction between the innerhypotube 622 and reinforced inner tube 680 is desirably provided withinthe tapered distal end 616 of the handle body 612, and thus ispositioned out of the range of travel of the sliding infusion port 630,which might otherwise catch on one of the tubular edges and interferewith the connection.

The inner lumen 702 continues from the inner hypotube 622, and throughthe entire reinforced inner tube 680 to the distal end 611 of theinsertion portion 608, seen in FIG. 11A. The inner lumen 702 provides achannel for the guidewire 604 (FIG. 10) from the connected guidewireintroducer 620 to the distal end of the catheter 600. In addition, theinner lumen 702 provides a passageway for an infusion guidewire of thepresent invention, as will be detailed below.

FIGS. 16A-16D illustrate various steps in the fabrication of thereinforced inner tube 680. FIG. 16A shows the entire length of the innertube 686 and distal segment 690. As can be appreciated by one of skillin the art, the entire length seen in FIG. 16A is desirably constructedof a single reinforced tube, wherein some of the reinforcement has beenremoved along the distal segment 690. In a specific preferred example,the entire length initially has 12 wires in a helical array 704, and thewires have been removed in the distal segment 690 to form a 4-wirehelical array 706. Again, as seen in FIG. 14, in a specific embodimentfor treating ischemic stroke the length L_(i4) of the distal segment 690is about 4 inches.

FIG. 16B shows a length L_(tt) of tip tubing 708 fused over the distalsegment 690 at a joint 710. The length L_(tt) is desirably about 1.5inches, and the tip tubing 708 is preferably a flexible polymer, such asPEBAX.

FIG. 16C shows the reinforcing sleeve 688 added to the assembly of FIG.16B. The total length of the reinforced inner tube 680 plus the tiptubing 708 is given as L_(i), and is desirably about 65 inches.Therefore, it will be understood that the length of the reinforced innertube 680 seen in FIG. 14, which added up to about 59 inches, is onlythat portion projecting distally from the strain relief tube 628 (FIG.13), and not including the length of the tip tubing 708. Also, asmentioned above, although a gap is seen between the inner tube 686 andthe reinforcing sleeve 688, the reinforcing sleeve is desirably shrinktubing fit tightly around the inner tube, and a smooth nose portion 712is provided at its distal end.

The tip tubing 708 is a 5-lumen construction seen in cross-section inFIG. 16E, with four smaller lumens 714 arranged in an arc on one side,and a larger guidewire lumen 716 on the other side. FIGS. 16Dillustrates four short longitudinal slots 718 skived in the surface ofthe tip tubing 708 to a depth that communicates with four smaller lumens714. In one specific embodiment, the distance A between the proximal endof the tip tubing 708 and the beginning of the slots 718 isapproximately 0.075 inches, while the length B of the slots 718 isbetween about 0.02-0.05 inches. As seen in FIG. 16E, the slots 718 arearranged in an arc around the tip tubing 708 that is less than 180degrees.

FIGS. 17A and 17B illustrate the clot removal components added to thedistal end of the inner tube of the embolectomy catheter 600. In FIG.17A, the tip tubing 708 has been shortened to a length C of no less than0.23 inches, and the distal end is provided with a shallow taper 720resulting in a distal tip diameter d_(tt) of about 0.019 inches. Amarker band 720 has been affixed around the tip tubing 708 at a distanceD of about 0.02-0.06 inches from the distal end of the slots 718, and atthe beginning of the taper 720. The marker band 720 is firmly affixed inthis location, such as by adhesive.

FIG. 17B shows a plurality of helical clot removal wires 724 affixed attheir distal ends 726 into the slots 718. In a preferred embodiment, theclot removal wires 724 are made of a super-elastic alloy, such asNitinol, and are bonded within the smaller lumens 714 and slots 718using a suitable adhesive. A fastener sleeve 728 may be provided to helpsecure the fixed ends 726 of the wires 724, and to provide a smootherouter surface at the junction.

The clot removal wires 724 extend helically in the proximal directionand each wraps around the distal segment 690 of the reinforced innertube 680. In a preferred embodiment, a distal wire pair 730 terminatesat distal free ends 732, while a proximal wire pair 734 terminates atproximal free ends 736. The free ends 732 and 736 are separated by asliding marker band 738. The free ends 732 and 736 and sliding markerband 738 are free to slide over the distal segment 690.

FIG. 18A is an elevational view of an unfinished tapered tip 740 that inFIG. 18B has been added to the assembly of FIG. 17B. The unfinishedtapered tip 740 has a length L_(tu) of no less than 0.30 inches, and aninner diameter d_(t) on its large end of about 0.04 inches. The smallend inner diameter tapers down to less than the diameter d_(tt) (FIG.17A), and thus the unfinished tapered tip 740 closely fits about thetaper 720, as seen in FIG. 18B. The excess length of the unfinishedtapered tip 740 is trimmed at the distal end of the taper 720 so that afinal tip 742 is formed. The tip 742 includes a proximal mouth 743.

FIG. 18C illustrates the final assembly of the outer tube distal sheath676 surrounding the distal end of the inner tube, with the helical clotremoval wires 724 shown in their stretched configurations 724′. Thedistal end 670 of the outer tube distal sheath 676 fits within the mouth743 of the tapered tip 742 to the extent of an overlap E ofapproximately 0.02-0.06 inches. As will be explained further below, thedistal sheath 676 is not bonded within the tapered tip 742, but ispermitted to slide with respect thereto.

FIG. 18C also illustrates the outer tube marker band 744 provided on thedistal sheath 676, and a plurality of infusion ports 746 formed alongthe side wall of the inner tube distal segment 690. As mentionedpreviously, the outer tube of the catheter 600 slides with respect tothe inner tube, and thus the marker band 744 slides with respect to thefixed marker band 722. The infusion ports 746 can be used for injectingcontrast media, medications, or fluids designed to dissolve clots. Thevarious uses of the embolectomy catheter 600 of the present inventionwill be more fully described below.

FIG. 19A is very similar to FIG. 18C, but illustrates the middle segment674 of the outer tube 650 joined to the distal sheath 676 at thejunction 677. In addition, the various components are shown incross-section so that the infusion ports 746 can be seen formed in theside wall of the inner tube distal segment 690 opposite from the sidewall seen in FIG. 18C. The number and spacing of the infusion ports 746can be varied, as will be explained below with respect to an embodimentshown in FIG. 22.

Exemplary Clot Removal Device

Actuation of the clot removal feature of the embolectomy catheter 600can be seen most clearly by comparison between FIGS. 19A and 19B.Specifically, the clot removal wires 724′ are shown in their stretchedand radially contracted configurations in FIG. 19A, and in their relaxedand radially expanded configuration in FIG. 19B, forming an expandedwire nest 750. This transformation is caused by proximal displacement ofthe outer tube, as indicated by the arrow 752. The clot removal wires724 normally assume the expanded configuration seen in FIG. 19B if theyremain unconstrained, but are held in the stretched configuration 724′by the presence of the surrounding distal sheath 676. Sliding the distalsheath 676 in a proximal direction 752 releases the wires 724, whichtend to radially expand, pulling their free ends 730 and 736 in a distaldirection. Because the pairs of wires 724 are wrapped around the distalsegment 690 on both sides of the sliding marker band 738, the slidingmarker band also is pulled distally. The relative spacing between thefixed marker band 722 and sliding marker band 738 provides an indicationto the operator about the configuration of the clot removal wires 724.

The outer diameter of the distal end of the embolectomy catheter 600 isextremely small for insertion within very small vessels of the brain,for example. In one particular embodiments, the embolectomy catheter 600has an outer diameter of about 3 French (Fr) (1 mm).

The expanded wire nest 750 has a diameter that is sized to closely fitwithin the affected vessel in which the clot has formed or lodged. Thatis, the wires 724 preferably contact and are slightly outwardly biasedagainst the inner luminal surface of the vessel. The luminal diameter ofthe target vessels of the present embolectomy catheter 600 arepreferably within the range of about 2.5-4.0 mm (0.090-0.110 in), andthus the diameter of the expanded wire nest 750 is also within the rangeof about 2.5-4.0 mm (0.090-0.110 in). Therefore, the expanded wire nest750 has an outer diameter that is between 2.5 and 4.0 times the diameterof the distal end of an exemplary 3 Fr catheter 600.

Each of the wires 724 may have a variety of cross-sections, butpreferably are circular in cross-section having a diameter of about0.002 inches. As mentioned above, a preferred material is asuper-elastic alloy, such as Nitinol, and the wires 724 are desirablyheat set into the nest shape 750 shown in FIG. 19B. The use of an alloysuch as Nitinol ensures that the wires 724 remain in their austeniticstate, and there is no deformation when they are in their stretchedconfiguration 724′ of FIG. 19A. Consequently, each of the wires 724 isspring biased toward its radially expanded configuration, facilitatingrapid deployment of the wire nest 750 upon proximal displacement of theouter to distal sheath 676.

In addition, each of the wires 724 has a helical configuration thatcreates a relatively dense tangle of wires in the nest 750 configurationshown in FIG. 19B. The particular number of wires 724 may be varied,although the smaller the catheter 600 the fewer number of wires that canbe accommodated. In a preferred embodiment of a 3 Fr catheter 600, thereare between 4 and 6 wires, and more preferably there are 4 as shown.

Wire Pusher Tool

FIGS. 20A and 20B are two views of a clot removal wire pusher 760 havinga handle 762 and a pusher portion 764. The pusher portion 764 isrelatively long, flat and thin and includes a shaft 766 having a lengthL_(sw) of about 1.5 inches and pair of side walls 768 on its distal tipforming a shallow U-shape. The shaft 766, on its distal end, has a widthw_(sw) and a thickness t_(sw) sufficiently small to fit in the annularspace 770 between the inner tube distal segment 690 and the outer tubedistal sheath 676 (see FIG. 19A). The wire pusher 760 is thus used topush the free ends 730 and 736 of the clot removal wires 724, andsliding marker band 738, in a proximal direction within theaforementioned annular space 770. In addition, the wire pusher shaft 766is sufficiently thin and flexible, having a thickness t_(wp), thatpermits the tool to flex outward at the distal tip 742. While the wirepusher 760 holds the clot removal wires 724 in their stretchedconfiguration, the outer tube distal sheath 676 is advanced in a distaldirection into close proximity with the distal tip 742. At the point atwhich the distal sheath 676 has sufficiently advanced to maintain theclot removal wires 724′ in their stretched configuration, the shaft 766of the wire pusher 760 can be retracted from within the annular space770. The distal sheath 676 is then displaced distally within the distaltip 742 to create the overlap region E seen in FIG. 18C. In an exemplaryembodiment, the shaft 766 has a thickness t_(wp) of about 0.003 inches,and the side walls 768 have a thickness t_(sw) of about 0.012 inches anda width w_(sw) of about 0.036 inches.

Operation of the Preferred Embolectomy Catheter

In operation of the embolectomy catheter 600, the guidewire 604 is firstinserted into the catheter 600 and advanced so as to project from thedistal end 611. The assembly of the catheter 600 and guidewire 604 isthen advanced through a target vessel and through a clot that ispreviously been located using well-known visualization means. Theleading guidewire 604 and tapered distal tip 742 facilitate passage ofthe catheter 600 through the clot. Additionally, the distal end of theouter tube distal sheath 676 is prevented from catching on the clot asthe catheter body passes therethrough by virtue of its insertion withinthe mouth 743 of the tapered tip 742. After a suitable length of thecatheter 600 is advanced past the clot, as can be verified by thelocation of the fixed marker band 722, the clot removal nest 750 isdeployed.

As mentioned previously, displacement of the sliding infusion port 630in a proximal direction relative to the handle body 612 (see FIG. 11A)causes deployment of the clot removal nest 750. That is, as best seen inFIGS. 12 and 12A, the sliding infusion port 630 is fixed axially withrespect to the outer tube 650. As the operator displaces the slidinginfusion port 630 along the channel 618 in a proximal direction, theouter tube 650 is pulled with respect to the reinforced inner tube 680.An infusion drip through the infusion port 640 hydrates and lubricateshydrophilic coatings provided on the inner surface of the outer tube650, and the outer surface of the reinforced inner tube 680. Moreparticularly, a lubricious coating is provided on these opposingsurfaces. This lubrication helps the outer tube 650 slide proximallyover the reinforced inner tube 680.

Displacement of the outer tube 650 over the reinforced inner tube 680results in the transformation from FIG. 19A to FIG. 19B. That is, theouter tube distal sheath 676 slides in the direction 752 to release thewires 724 to form the expanded wire nest 750. Again, displacement of thesliding marker band 738 toward the fixed marker band 722 indicates tothe operator that deployment of the wire nest 750 has occurred.Desirably, the outer tube distal sheath 676 that constrains the clotremoval device 724 in its collapsed configuration has a substantiallylower column strength than that portion of the reinforced inner tube 680about which the clot removal device is mounted. This helps increaseflexibility of the catheter 600 at the distal end, while still ensuringadequate column strength to enable the telescoping deployment. Theoperator may, if desired, tighten the bolt 646 to maintain the relativepositions of the inner and outer tubes so that the clot removal device724 is held in its deployed configuration.

At this point, the entire catheter 600 is retracted in a proximaldirection over or with the guidewire 604 to cause the expanded wire nest750 to become entangled within the clot. Rotation of the catheter 600,or rotation of the reinforced inner tube 680 alone, helps the wire nest750 to entangle and entrap the clot. This portion of the procedure issimilar to that shown in FIGS. 8D-8F in conjunction with anearlier-described embodiment of the present invention.

Operation of Alternative Embolectomy Catheters of the Present Invention

FIGS. 21-24 illustrate various clot removal techniques that can bepracticed with one or more of the specific catheter embodimentsdescribed herein. Although certain techniques, such as balloon occlusionand aspiration, are well-known in the art, the present inventors believethat the over-the-wire catheters of the present invention permit novelcombinations that provide significant advantages over the prior art.That is, passing a guidewire first through the clot provides a vehicleover which a variety of clot removal devices can be passed to thedownstream side of the clot. Access to both sides of clot provides anoperator with flexibility previously unknown. Although some devices ofthe prior art show catheters passing through the clot to, for example,expand a balloon on the downstream side of the clot, none of thesedevices are suitable for removing clots in extremely small vessels.Consequently, the present invention provides devices and methods forsmall vessel clot removal that are a significant advance in thetreatment of ischemic stroke, for example.

FIGS. 21A and 21B illustrate the basic advance of the present inventionin passing a guidewire 800 through a clot 802. The guidewire 800 isshown having a tapered tip 804, and may be especially designed topenetrate a clot 802 as, for example, with the provision of a sharpenedtip. An outer catheter shaft 806 is shown advanced into close proximitywith the clot 802, which location can be easily reached with the use ofmarker bands and radiographic visualization.

FIG. 21B illustrates the advancement of an inner catheter shaft 808 overthe guidewire 800. One significant advantage of first passing theguidewire 800 through the clot 802 is that a first inner catheter shaft808 can be introduced, utilized, and then removed, and a second cathetershaft can be introduced. In this manner, a variety of treatments and/ordevices can be applied to remove the clot 802 utilizing a singleguidewire 800 which remains in place. This saves time and reduces traumato the patient.

FIG. 22 is a cross-section through a vessel showing an infusion catheter820 having an expanded balloon 822 on its distal end after having beenadvanced over a guidewire 824 and through a clot 826. As mentioned abovewith respect to the infusion ports 746 seen in FIGS. 18 and 19, theinfusion catheter 820 can have variable infusion port spacing along itslength. More specifically, the infusion catheter 820 includes a proximalregion 830 with few or no infusion ports, a middle region 832 embeddedin the clot 826 with infusion ports that are more concentrated in thecenter, and a distal region 834 with a large concentration of infusionports. The relative flow of fluid through these infusion ports isillustrated schematically.

In a preferred embodiment, fluid suitable for breaking up the clot 826is introduced through the ports of the infusion catheter 820. Because ofthe balloon 822, the fluid stays in the region of clot 826 for moreeffective clot dissolution. In addition, injecting dissolution fluid inthe middle of the clot 826 facilitates its internal breakup.Furthermore, the larger flow of fluid from the distal region 834 helpscreate a pressure gradient which forces the clot 826 in the proximaldirection toward the catheter shaft 836.

FIGS. 23A and 23B illustrate a catheter shaft 840 that has a multiplelumen cross-section with a plurality of aspiration ports 842 in additionto the central guidewire port 844. The catheter shaft 840 can be used inconjunction with the arrangement shown in FIG. 22 to aspirate the clot826 as it breaks up.

FIG. 24A illustrates a clot removal device similar to that shown in FIG.22, with the addition of an expandable receptacle 850 shown extendedfrom the distal end of a retractable catheter sheath 852. The infusioncatheter 854 and balloon 856 have been advanced over a guidewire 858.The use of suction, as indicated by the arrows 860, may be combined withthe expandable receptacle 852 to capture the dissolving clot 862 as itmigrates in a proximal direction.

FIG. 24B shows an outer catheter shaft 870 adjacent a clot 872 with aninfusion catheter 874 and expandable clot trap 876 advanced over aguidewire 878 through the clot. The expandable clot trap 876 may be anyof the embodiments described previously, and is shown as individualspring members attached at both ends to the infusion catheter 874. Awebbing 880 may also be provided to help capture small particles ofdissolving clot material. Infusate 882 from the catheter 874 is alsoshown to facilitate clot breakup. Again, aspiration may be combined withthis arrangement.

FIG. 24C is similar to the configuration of FIG. 24B but includes anexpandable clot trap 890 comprising a plurality of umbrella-like strutswith a webbing 892 therebetween. A collar 893 may be provided forcollapsing the clot trap 890. Again, the infusion catheter 894 and clottrap 890 have been advanced over a guidewire 896 that had previouslypenetrated through the clot 898.

Finally, FIG. 24D is an arrangement similar to that shown in FIGS. 24Band 24C, but includes a clot removal trap 900 made up of a plurality ofcurvilinear spring wires 902 projecting from the end of the infusioncatheter 904. The spring wires 902 may pass through individual lumensformed within the infusion catheter 904, and preferably have roundedtips to prevent vessel perforation. Once again, a guidewire 906 is firstadvanced through the clot 908.

Infusion Guidewire

In addition to the advantages provided by a guidewire that permitssustained access to downstream side of clot, the present inventioncontemplates the use of a special type of guidewire that can be used toinfuse fluid. Although small infusion catheters are known in the art,the present invention is believed to be the first device that can infusefluid on the downstream side of a clot in extremely small vessels, suchas the vessels of the brain. This feature, in conjunction with thepreviously described advantages of locating a guidewire through a clotas a vehicle for clot removal catheters is a significant improvement onthe prior art.

A specific example of an infusion guidewire 920 of the present inventionis schematically shown in FIGS. 25A and 25B. The infusion guidewire 920comprises an inner wire member 922 and an outer sleeve member 924. Theguidewire 920 is shown inserted through a micro-catheter 926 having aproximal region with a length L₁, a tapered middle region with a lengthL₂, and a distal region with a length L₃. These lengths may be forexample: L₁=100 cm, L₂=20 cm, and L₃=20 cm; with the axial lengths shownschematically.

The wire member 922, has an outer diameter of about 0.007 inches. Thesleeve member 924, in turn, has an inner diameter of a slightly greatersize, preferably about 0.008 inches. The outer diameter of the sleevemember 924 is preferably about 0.010 inches. The inner diameter of thedistal region L₃ of the micro-catheter 926 closely fits around thesleeve member 924, however, in the proximal region L₁, an annular space928 is creating between the sleeve member 924 and the inner lumen 930 ofthe micro-catheter 926.

The wire member 922, by virtue of its slightly smaller dimension, may bedisplaced longitudinally within the sleeve member 924, as indicated bythe arrow 932 of FIG. 25B. A plurality of side ports 934 are provided inthe sleeve member 924 in the middle region L₂ of the micro-catheter 926.Therefore, after the wire member 922 has been retracted into theposition shown into 25B, fluid infused through the annular space 928 canpass through the side ports 934 into a lumen 936 of the sleeve member924, and from there out of its distal tip 938.

In use, the infusion guidewire of the present invention is advancedthrough blood vessel toward a clot 950, as seen in FIG. 26A. The wiremember 922 and sleeve member 924 may be advanced independently, or intoproximity with a clot 950 within the micro-catheter 926. FIG. 26Billustrates the infusion guidewire comprising the wire member 922 andsleeve member 924 having penetrated the clot 950 to a downstream side.Subsequently, as seen in FIG. 26C, the wire member 922 is withdrawn asindicated by the arrow 952, leaving the sleeve member 924 in place onthe downstream side of clot 950. Fluid can then be infused through thesleeve member 924, as indicated at 954 in FIG. 26D. Such fluid can be,for example, medications, clot dissolution chemicals, or contrast media.

The advantages of being able to infuse fluid on the downstream side of aclot have been explained previously, but one particular advantage is theability to inject contrast media to better visualize the size andposition of the clot 950. Thus for example contrast media may beinjected at 954 as seen in FIG. 26D in anticipation of use of one of theclot removal devices of the present invention.

Prior to introduction of an embolectomy catheter of the presentinvention, the wire member 922 is desirably reinserted within the sleevemember 924 to provide suitable rigidity, as seen in FIG. 27A.Thereafter, as in FIG. 27B, an embolectomy catheter 960 is advancedalong the infusion guidewire and through the clot 950, as indicated bythe arrow 962. Subsequently, the telescoping element of the embolectomycatheter 960 is retracted, as indicated at 964 in FIG. 27 c, to releasea clot removal device 966, such as the helical wires described abovewith respect to FIGS. 18 and 19. Of course, any of the embolectomycatheters of the present invention can be substituted. Finally, as seenin FIG. 27 d, the embolectomy catheter 960 is retracted as indicated thearrow 970 to cause the clot removal device 966 to become entangled withand remove the clot 950.

It is to be appreciated that the invention has been described hereinwith reference to certain exemplary embodiments only, and no effort hasbeen made to exhaustively describe each an every possible embodiment ofthe invention. For example, the specific dimensions given herein are notto be considered limiting. Indeed, as those skilled in the art willappreciate, various additions, deletions, modifications and/oralterations may be made to he above described embodiments withoutdeparting from the spirit and scope of the invention. It is intendedthat all such additions, deletions, alterations and modifications beincluded within the scope of the following claims.

1. A method for removing obstructive matter from a vessel of a patientcomprising: advancing a distal end of a guidewire toward obstructivematter within said vessel; advancing an embolectomy catheter over saidguidewire; advancing a distal end of said embolectomy catheter throughsaid obstructive matter; retracting an outer tube of said embolectomycatheter relative to a distal tip of said embolectomy catheter, therebyremoving a constraint on an obstruction matter capturing receptacle onsaid embolectomy catheter; expanding said obstructive matter capturingreceptacle; and retracting said embolectomy catheter so as to capturesaid obstructive matter within said obstructive matter capturingreceptacle.
 2. The method of claim 1, wherein expanding the obstructivematter capturing receptacle on said embolectomy catheter furthercomprises deploying said obstructive matter capturing receptacle from anunexpanded state to a radially expanded state.
 3. The method of claim 1,wherein advancing a distal end of said guidewire through saidobstructive matter within said vessel is followed by preventinglongitudinal retraction of said guidewire.
 4. The method of claim 1,wherein the step of displacing a distal tip of said embolectomy catheterrelative to the outer tube of said embolectomy catheter comprisesadvancing an actuator within said embolectomy catheter.
 5. The method ofclaim 1, wherein expanding the obstructive matter capturing receptacleon said embolectomy catheter further comprises radially expanding aplurality of wires from said embolectomy catheter.
 6. A method ofremoving an obstruction within a vessel comprising: inserting aguidewire into said vessel of a patient; advancing said guidewire towardsaid obstruction; advancing a catheter over said guidewire advancing atapered distal tip of said catheter through said obstruction; advancingsaid catheter until an obstruction removal device of said catheter hasat least partially passed through said obstruction; separating thetapered distal tip of said catheter from an outer tube of said catheter;deploying said obstruction removal device from an unexpanded state to anexpanded state; and capturing said obstruction with said removal deviceby retracting said obstruction removal device.
 7. The method of claim 6,wherein advancing the catheter over said guidewire until the obstructionremoval device of said catheter has at least partially passed throughsaid obstruction further comprises passing said distal tip of saidcatheter through said obstruction.
 8. The method of claim 6, whereinsaid deploying said obstruction removal device from an unexpanded stateto an expanded state further comprises manipulating a deploymentactuator at a proximal end of said catheter which is operativelyconnected to said obstruction removal device.
 9. The method of claim 6,wherein deploying said obstruction removal device from an unexpandedstate to an expanded state further comprises radially expanding aplurality of elongated members.
 10. The method of claim 6, whereincapturing said obstruction with said removal device by retracting saidobstruction removal device further comprises entangling said obstructionwith elongated members of said obstruction removal device.
 11. Themethod of claim 6, wherein deploying said obstruction removal devicefrom an unexpanded state to an expanded state further comprisesretracting said outer tube on said catheter relative to said obstructionremoval device.